Electric switches of a switching system in the form of low-voltage circuit breakers in plug-in technology are known. The circuit breakers can be moved in and out in a plug-in frame of a switch cabinet and have a switching contact system with a contact arrangement and an arc quenching chamber. The contact arrangement has a stationary and a moving switch contact, which can be moved by a drive mechanism to close and open the switch. The drive mechanism includes a drive device for a switching shaft which, to close and open the switch contacts, can be rotated from an off position to an on position and vice versa. In the off position, the switch contacts are isolated from each other, and in the on position the switch contacts rest on each another. The drive device further comprises a spring of a force store and a switching lock with a latching mechanism for latching the loaded spring, wherein the force store provides the energy to close the contacts.
The circuit breaker is withdrawn out of its operating position into its removal position by a movement drive which has a withdrawal shaft.
For occupational safety reasons, the spring store of the switching lock must be unloaded during the removal of the circuit breaker from the plug-in frame, for example for maintenance purposes.
Therefore, the spring of the spring store is automatically unloaded during the withdrawal into its removal position, as is already known from DE 101 53 108 C1, DE 100 65 090 C1 and EP 0 048 042. The interaction of switching lock, latch and spring store of a low-voltage circuit breaker is known from DE 100 10 727 C2 and DE 101 20 783 C1.
In addition, a specific mechanism for unloading the spring of the spring store during withdrawal is known from DE 10 2004 021 455 A1. The mechanism unloads the spring store on the basis of the revolutions of the withdrawal shaft at a defined location of the movement travel between a test position and the removal position. This is carried out as a so-called empty switching action by unlatching the latching mechanism via a latch, in particular the switch-on latch, which functions as a “triggered latch”. The latch is released by a latching shaft after the latching shaft has been moved by the withdrawal shaft into its unlatching position.
The mechanism known from DE 10 2004 021 455 A1 comprises a linkage which is constructed as a linear slider and converts the rotational travel covered by the withdrawal shaft into a linear movement. This movement in turn rotates an unlatching shaft, which releases the latch when it reaches its unlatching position, so that the latch of the latching mechanism can unlatch and the storage spring is unloaded.
The linkage includes a bending element, which resets the linear slider via a tension spring following the rotation of the unlatching shaft. As a result, the unlatching shaft is released again following the unloading and the storage spring can be loaded again.